【作者】 张峰；

【导师】 刘雄； 阚建全； 赵国华；

【作者基本信息】 西南农业大学 ， 食品科学， 2005， 硕士

【摘要】 青稞（Hordeum Vulgate L.var.nudum Hook.f）是一种青藏高原地区的特色农作物,其富含生理活性物质β-葡聚糖,近年来受到广泛的关注。本文以青稞麸皮为原料,采用热水浸提法。通过单因子试验确定了从青稞麸皮中提取β-葡聚糖粗品的工艺参数,研究了各提取因素对青稞β-葡聚糖粗品得率影响的主次顺序,确定了最佳提取参数,并进行了可行性验证。β-葡聚糖粗品经脱蛋白、乙醇醇析、硫酸铵分级、透析、DEAE-52纤维素柱层析和SephadexG-100凝胶柱层析得到β-葡聚糖A和B,确定了用醇析法和柱层析法纯化糖的参数条件,得到了纯化的β-葡聚糖,并对β-葡聚糖A进行了纯度鉴定及理化性质的研究。本研究主要结果如下: （1）青稞中β-葡聚糖在麸皮中含量较高（5.78%）,而在青稞面粉中含量较低（2.21%）,即青稞β-葡聚糖主要分布在糊粉层细胞壁中。 （2）以青稞麸皮为原料提取β-葡聚糖前进行预处理（高温烘干和乙醇回流）对β-葡聚糖得率影响不大。 （3）试验结果表明,影响青稞中β-葡聚糖得率的各因素主次顺序是pH值、时间和料水比,最佳提取工艺参数为:pH值为9、时间2.0h、料水比1:15、50℃下提取两次,得率为6.65%,纯度64.72%。 （4）调节多糖液的pH值至4.5,去除部分蛋白类物质,进行硫酸铵分级沉淀,最后进行乙醇醇析,得到纯度为88.7%的β-葡聚糖,再经DEAE-52纤维素柱层析和Sephadex G-100凝胶柱层析得到一种均一分子质量的β-葡聚糖,得率为0.45%（以青稞麸皮干基计）。 （5）β-葡聚糖A的单糖组成是由葡萄糖组成。样品的分子质量为3.0×10⁵道尔顿;分子结构中存在β-型糖苷键;所得β-葡聚糖不溶于乙醇、乙醚、丙酮等有机溶剂,粘度为42mPa·S,[α]_D²⁰（H₂O）为:-95.3度;与碘-碘化钾溶液的反应不显色,说明它是非淀粉类多糖,与斐林试剂反应、双缩脲反应、三氯化铁反应、CTAB反应、280nm吸收均为阴性,说明它是不含单糖、蛋白质、多酚类物质、核酸等的中性多糖。更多还原

【Abstract】 Highland barley {Hordeum Vulgare L var. nudum Hook.fi is a kind of characteristic crops in Tibet region .Considerable attention has been focused on it for its abundant P -glucan. In this paper , β-glucan has been extracted by means of hot water with highland barley bran as raw materials .Based on the single factor experiment , technological parameters of extraction has been defined and the effects of factors on extraction has been described. The feasibility of experiment results has been verified.. A P -glucan was obtained from crude β -glucan by removal of protein . precipitation by ethanol , ammonium sulfate fractionation , dialysis, cellulose column chromatography and Sephadex G-100 column chromatography . The optimized conditions of precipitation by ethanol and column chromatography have been determined. Purity and physicochemical property of A P -glucan has also been determined and analyzed. The results showed as follows.1. The content of P -glucan is highest in highland barley bran （5.78% ）。 It indicated that P -glucan was found mainly in aleurone layer of highland barley.2. The effect of pretreatment （drying with high temperature and ethanol refluxing ）on extraction of P -glucan was not significant.3. The order of major and secondary factors influencing β-glucan extraction was pH , temperature, time and stock ratio. The optimum extraction conditions were: pH 9, 50℃,time 2h, stock ratio 1:15. and two times of extraction. The yield from barley bran was 6.65%,The purified preparation contained 64.72% P -glucan.4. The purification process of P -glucan was confirmed: removal of protein by adjusting pH. ammonium sulfate fractionation. precipitation by ethanol. β-glucan with 88.7% purity was obtained. Then cellulose column chromatography and Sephadex G-100 column chromatography was used to isolate it and A P -glucan with analogous molecular weight was gained.Its ratios was 0.45%.5 .Monosaccharide of A P -glucan was made of glucose. Molecular weight of sample A was 3.0 × 10⁵ Dal, Sample was composed of glucosyl bond.Sample A was insoluble in ethanol, aether and acetone. Its viscosities was 42 mPa · S. [α ]D²⁰ （H₂O） was -95.3 .They had no color reaction with potassium iodide, which explained that they were non-starch polysaccharide. Their reaction with Fehling reagents ,biuret reagents, ferric chloride reagents, CTAB reagents and their absorption in 280nm were negative. These results showed that they did not contain monosaccharide, protein, polyphenols and nucleic acid and they were neutral, polysaccharide.更多还原